When a 90-ohm resistor is cut into 3 equal parts, the resistance of each part will change. The total resistance is divided equally among the parts.
Since the resistor is cut into 3 equal pieces, the resistance of each part will be:
\[
R_{\text{part}} = \frac{R_{\text{total}}}{3}
\]
So for a 90-ohm resistor:
\[
R_{\text{part}} = \frac{90 \, \Omega}{3} = 30 \, \Omega
\]
Therefore, each of the 3 pieces will have a resistance of
30 ohms.